Patent GB-519519-A (GB)
Title: Improvements relating to control systems for aeroplanes
IPC: B64C13/00
Filed: 1938-06-23
Abstract: 519,519. Controlling aircraft. AIRSPEED (1934), Ltd., TILTMAN, A. H., and ELLISON, A. E. June 23, 1938, Nos. 18705 and 36607. [Class 4] In'a control circuit for aeroplanes in which a manually-operated flying control, which may be either the foot-operated rudder control or the hand-operated control column for ailerons and elevator, is mounted on a housing containing mechanism for operating at least one shaft or member which passes out of the housing for connection to the control surfaces, at least one auxiliary component which imparts movement to, or has movement imparted to it by the control members actuated by the flying control, is. mounted on or built into the housing, the control unit with the auxiliary components constituting a single unit which can be mounted in or removed from the aeroplane, as a whole. The auxiliary components may comprise:-a wheel brake control, automatic pilot control means; a servo-motor device ; means for automatically recording the movements of the rudder; means for applying bias to the operating members of the control surfaces. There may also be included connecting means for dual control; means for adjusting the pedals or column to suit the reach of the pilot and means for locking the control when not in use. As shown applied to a rudder control, Figs. 1-3, pedals 1, 1<1> are mounted on arms 2, 2<1> which are carried on shafts 4, 4' entering the box 3. These shafts carry bevel wheel sectors 6, 6' forming the sun wheels of a differential gear of which the planet is a bevel pinion 7. The pinion 7 is mounted on a shaft 8 connected by a universal joint 9 to another shaft 10 passing through the bottom of the box 3 and having the rudder control lever 5 mounted on it. The upper end of the shaft 8 can be moved backwards and forwards about the joint 9, thus adjusting the pedals 1, 1<1> to suit pilots of different heights. Adjustment is by means of the screw threaded rod 18 and sleeve 17, Fig. 2, and may be effected from a remote point through the flexible shaft 20. In the box 21 secured to the box 3 is a differential control valve of known type for differential regulation of the brakes on the landing wheels in accordance with the rudder position. This valve is linked to the shaft 10 through the gear sectors 23 and 24. A portion 5' extending at right-angles to the lever 5 enables connection to be made to a duplicate set of controls. For biassing and centering, a rod 26 is pressed, by a spring device 28 mounted on the box 3, against the edge of a plate 25 secured to the shaft 10. An adjustment 26a is provided whereby the rod 26 may be swung to one side to apply a bias. A hydraulic motor 30, having a piston 31 with a piston rod 32 connected to an automatic pilot or may be used as a servomotor. An additional piston 37 acts as a vibration damper. 40 is a valve of known type for use in connection with the servomotor. 42 is a pen for recording movements of the control on the revolving drum 43. Spring stops 44 are provided to limit the travel. An adjustable spring (not shown) may act on the plate 25 to vary the control stability without applying an asymmetric bias. In the form shown in Fig. 4 a control column 1 is mounted on the box 3, having a control wheel (not shown) at its upper end, connected to a chain 5 having two runs which pass round sprocket wheels 6 so arranged that movement of the control column effects no subtantial movement of the chains. The chains pass round sprocket wheels 7 on a shaft 8 which is connected to the ailerons. Fore and aft movement of the control column causes movement of the sprocket 14 through the toothed sector 9 and thus effects elevator control. The toothed sector is freely pivoted on the control column and connected to the column by a link 13 which is pivoted to a nut 12 on a screwed sleeve 18 rotatable on the column so that the distance of the column from the pilot may be adjusted. The column may be telescopic. Servo, recording, and damping means 30-43 are shown identical with those in Figs. 1-3. They are applied to the aileron control, but might be applied to the elevators. Biassing and centering means are also applied to a plate, as described above, which is mounted on a shaft 51 and extends to form a geared sector meshing with a pinion on the shaft 8. The stops 44 co-operate with a member 44<1> rotating with the elevator shaft 15. The top of the box 3 is covered by a flexible rubber cap 16. In the dual control system shown in Fig. 7, the portions 5' on the rudder controls are connected by a bar 80. The aileron and elevator shafts - are connected by internally splined tubes 81 engaging with projecting ends of the shafts 8 and 15. The control systems are shown bolted between pairs of fore and aft bearers 83. Locking means comprise a bar 85 having a hooked end 86 to engage with the projections 100 (Fig. 1) on the rudder pedals, and lock with the control column by means of a spring clip 90. The bar 88 then prevents entry 'into the pilot's seat. The means of adjusting the rudder control may. be replaced by mechanical or hydraulic equivalents. 'Thus each pedal may be connected to a piston in a hydraulic cylinder, the respective ends of which are connected by pipes and the two pipes connected to the ends of a third cylinder, the piston of which is moved by hand to effect adjustment of the pedals in the same direction. The locking means for the rudder pedals may be self contained For example, the pedal arms may be telescopic, the outer part carrying a pin, and the pedal may be turned so that the pin enters a recess in a fixed part of the unit. The control column may have a lateral movement to replace the wheel. Any of the auxiliary. devices described may be omitted, the openings in the box being covered by plates. According to the second Provisional Specification the control column may be telescopic for adjustment purposes. Further, the box or casing may be arranged to rock with the column about a transverse shaft secured to the aeroplane and be provided internally with a curved rack geared to a shaft which projects through the casing and is connected to the elevators, the hand wheel or lateral movements of the column being transmitted to a second shaft by a chain as described above. In another construction in which the casing rocks with the column, the transverse shaft is cranked at its middle part and a bevel wheel is mounted on the outside of the crank so as to rotate about an axis at right angles to the shaft axis. The shaft of a sprocket wheel mounted inside the casing and over which the chain from the hand wheel runs, is connected by a universal joint to the shaft of the bevel wheel. A second bevel wheel geared to the first is mounted on a hollow shaft which surrounds the transverse shaft, at one and end projects from the casing and is connected to the ailerons. The casing is provided inside with a curved rack which is geared to a second hollow shaft surrounding the other part of the transverse shaft and projecting from the casing. The hand wheel may be of the spokeless type, comprising a semi-circular tube arranged to slide upon an inner, rail on ball bearings. The movement of the wheel may be transmitted down the control column by cables, the ends of which are secured inside the tube near its free ends.